Thread: Treadmill motor???

Originally Posted by Tinkerer77

Sorry Bob, I think you have me there, I think without looking at the unit it is 220 to 380, I raised the voltage issue with the industrial electrician at work and he thought that I would really only notice that power voltage issue at higher loads, the vfd does have a max current setting in it, I was very sceptical about it at first but it has impressed me so far, my only issue is that I need to adjust my run down time as at max speed on my 260 is 2600rpm it trips out with a run down fault as it can't stop the motor in the time frame I have set that parameter.

The Ecogoo units are nominally 220 to 380V, but the input is usually be 220V +/- 10% which makes a nominal maximum 244V and in most cases they can go a bit more.

The outputs on the Ecogoo SP-3P VFDs will scale with the input, so 220V in becomes 380V out, but if 240V goes in then 415V will come out.

On the 240V SP input, to 240V 3P output VFDs, most are sold as 220V VFDs but the same applies 240V SP in means 240 3P out.
Same for the 380V 3P in - to 380V 3P out , if they are run on 415V 3P in then they will normally give 415V 3P out.

Originally Posted by Metalmachine

Ok, starting to make sense, thanks Bob and neevo.

I did find some independant info (wasn't hard to find) and a video demo running a 3 phase motor from a single phase but I won't elaborate. The inefficiency and probability of damage plus the effort is guiding me back to option 1, especially the realisation about increasing the complexity of the switchgear to get a reverse direction option (which I prefer to have for thread cutting)

But thanks for coming with me on the journey.

I probably will run it for a little while on the 2840rpm single phase motor, it will be temporary, but will invest in a VFD when it becomes feasible in the budget (other things are more urgent as mentioned)

Thanks very kindly for the help.

Steve.

As long as you are aware that most lathes use a motor and a switch called contactor with a current limiting device. This is so that if things go pear shaped the power will turn off before very serious damage occurs to the machine and/or motor. The currents I'm talking about are in between what the lathe motor and circuit breaker are rated for.

Let's say you are running a 1/2HP motor on a 10A circuit (usually has a 16A breaker). A 1/2HP motor might draw about 2A max. If you continuously overload or jam the motor the motor might start to draw more than 2A but nowhere near enough to trip the breaker. This will overheat the motor and while the motor may have an inbuilt thermal fuse a lot of mechanical damage can take place before it trips.

Circuit breakers are designed to protect wiring and not machinery, and in most cases circuit breakers will be too slow to act before serious damage is done. Single phase machines often use small 3P contactors which allow a current limit to be set but they are expensive if purchased new. VFDs usually have built in current limitation so a contractor is not needed.

Alternatively a simple precautionary approach is to run any belts slightly loose so they slip in case of a mechanical jam but I wouldn't call this a best practice way of dealing with this problem.



.

I think running belts a bit loose to learn is also a good move. My Hercus was a flat belt before I changed it to a belts and that saved me a couple of times as I was learning.

That is food for thought, thanks Bob.

I have taken a peek at the switchgear and contactors on lathes and mills at my old work but thought I'd keep it simple on this low power machine, the motor has inbuilt protection, its a full duty motor but unsure how fast it would act, probably not fast enough. I'm confident I wouldn't crash the machine, learnt my lessons as an apprentice machinist long ago, but will have to think further about this.

Cheers,
Steve.

Originally Posted by Metalmachine

That is food for thought, thanks Bob.

I have taken a peek at the switchgear and contactors on lathes and mills at my old work but thought I'd keep it simple on this low power machine, the motor has inbuilt protection, its a full duty motor but unsure how fast it would act, probably not fast enough. I'm confident I wouldn't crash the machine, learnt my lessons as an apprentice machinist long ago, but will have to think further about this.

The loose belts idea is worthwhile even with other forms of safety as most machine crashes create most mechanical damage well before any protections can kick in. In some situations a VFD with a brake resistor can really help reduce the number of times the chuck keeps going around before it stops but this can lead to other issues like the chuck/workpiece coming off.

The E-stop mushroom switch at hip height on my MW lathe cuts the power to the VFD which stops everything in ~1.5s (which is the same as the standard deceleration time of 3s) but has the benefit of also providing electrical isolation. Same setup on my WW lathe but this has a standard deceleration time of 3s to cope with large pieces of wood.

Different people have different takes on this aspect of safety.

I strongly advise against any form of motor braking on a Hercus lathe. I’ve had my faceplate and 4-jaw unscrew from the spindle on my 260. In the case of the faceplate, I hadn’t even switched the lathe off. I just wound the RPM down and my programmed deceleration rate was enough for it to unscrew. Happily it dropped onto the ways and slowly came to rest without any damage.

The 4 jaw unscrewed itself, but was luckily prevented from falling onto the ways by the length of 20mm square stock that remained inside the spindle bore. It scared the bejesus out of me and made the most awful noise. Those Hercus spindles must be well hardened, because there wasn’t a mark on it. The stock was badly chewed up though.

I frequently swap between my 3 jaw, 4 jaw and collect chucks, so they don’t bind onto the spindle thread as they would if they were left in place for a period of time. So if you own a Hercus lathe and you’re a frequent chuck-swapper, I urge you to avoid braking.

Originally Posted by jack620

I strongly advise against any form of motor braking on a Hercus lathe .

In general I would agree but Ive experimented with deceleration on my chucks a fair bit.
It's only a Hercus 9" (slow model) so it rarely gets used at higher speeds (using a VFD).
The chucks must be gummed up just enough so that even with the 4 jaw I can use a 1s stop time and it it does not move. I've thus set my stop time to 1.5s.
This is of course with nothing in the chucks but large heavy workpieces usually mean slower speed so if its less of an issue.
I have a chuck holding draw bar that I can use - if I remember - when holding large/heavy workpieces and need to operate at higher speeds.
The drawbar does block the spindle bore, but the bore is not that big anyway so if I'm using the bore it's going to be with smaller workpieces.

Hi Guys,

I've never had any issue with the chucks on my Myford coming unscrewed, however I was talking to a chap that had a 10" inch faceplate unscrew on him ! He said that he has cured his by putting a chamois leather washer behind the chuck which he says reduces the risk of a chuck unscrewing, but makes it much harder to unscrew when changing them. I gather from him that he cut a washer out of a chamois wash cloth.

I've no idea if or how well this works, but it seems a simple fix !

Is it possible to drill the backplate for a brass set screw or two to allow minor turning in reverse?

If you want to turn in reverse a good solution is an ER40 collet chuck with a morse taper arbor (MT4 for a 260. MT3 for a 9C, I think). A draw bar will ensure the morse taper doesn't let go. ER40 will allow you to hold stock up to at least 26mm.

Yeah good point. I have that setup in ER32 but that’s limited to about 20mm I think. I was going to add a 5C collet chuck at some point but that still wouldn’t be locked to the spindle.

There is another option.
Install a 1400 rpm, single phase 1/2HP 240v motor.
This is what I have on my small lathe, it has run very reliably for many years.

Paul

Originally Posted by neevo

Yeah good point. I have that setup in ER32 but that’s limited to about 20mm I think. I was going to add a 5C collet chuck at some point but that still wouldn’t be locked to the spindle.

There are extended ER32 collet sets that go as high as 25mm. I cough a set a while back and have used teh 22mm collet a few times.

Originally Posted by BobL

There are extended ER32 collet sets that go as high as 25mm.

Available here: https://www.ebay.com/itm/Gloster-ER3...r=641094243536

However it might be more cost effective to buy an ER40 collet chuck and the larger sized collets locally:

https://www.ausee.com.au/shop/item.aspx?itemid=3839

Originally Posted by jack620

Available here: https://www.ebay.com/itm/Gloster-ER3...r=641094243536

However it might be more cost effective to buy an ER40 collet chuck and the larger sized collets locally:
https://www.ausee.com.au/shop/item.aspx?itemid=3839

Couldn't see any ER40 stuff for sale at Ausee.

I got the ER32 extended set as I already had a set of standard ER32 collets which I bought about 10 years ago from CTC tools .
The set only cost $80 and shipping was $40 (ouch!) but they are a very nice set.
https://www.ctctools.biz/er-collets/...eatured&page=3

A couple of years back I bought a set of precision ER16s from CTC as I have a tiny work envelop on my Hercus mill and the ER16 chuck is much less obtrusive than the ER32 into the workspace.
These only cost $70 including shipping. I have used these much more than the ER32s.